The new cultivar is the product of chance discovery. The new variety originated as a naturally occurring mutation of an unpatented, unnamed variety of Pelargonium cordifolium. 
The new variety was discovered by the inventor, Lance Reiners, a citizen of the United States, on Aug. 13, 2009 in the home garden of the inventor in Santa Cruz, Calif. After identifying the new variety as a potentially interesting selection, the inventor continued confidential testing and propagation of ‘CAROLINE'S CITRINE’ for approximately 2 years, assessing stability of the unique characteristics of this variety.
Asexual reproduction of the new cultivar ‘CAROLINE'S CITRINE’ was first performed at a commercial nursery in Watsonville, Calif. by vegetative cuttings in March of 2010. Access to all plants was restricted, as plants were kept in a locked greenhouse not open to the public. Through subsequent propagation by vegetative cuttings, multiple generations have been reproduced, which have shown that the unique features of this cultivar are stable and reproduced true to type.